# Copyright 2016 The TensorFlow Authors. All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
# ==============================================================================
"""Converts assert statements to their corresponding TF calls."""

import gast

from nvidia.dali._autograph.core import converter
from nvidia.dali._autograph.pyct import templates


class AssertTransformer(converter.Base):
    """Transforms Assert nodes to Call so they can be handled as functions."""

    def visit_Assert(self, node):
        self.generic_visit(node)

        # Note: The lone tf.Assert call will be wrapped with control_dependencies
        # by side_effect_guards.
        template = """
      ag__.assert_stmt(test, lambda: msg)
    """

        if node.msg is None:
            return templates.replace(
                template, test=node.test, msg=gast.Constant("Assertion error", kind=None)
            )
        elif isinstance(node.msg, gast.Constant):
            return templates.replace(template, test=node.test, msg=node.msg)
        else:
            raise NotImplementedError("can only convert string messages for now.")


def transform(node, ctx):
    node = AssertTransformer(ctx).visit(node)
    return node
